<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<script>
var a = 10.949543598
var b = parseInt(a)
console.log(b);
console.log(parseInt("12.3ab33"));
console.log(parseFloat("12.3ab33"));

console.log(typeof NaN)   // 用 typeof 测试出来的类型都是小写的
console.log(typeof (1 / 0))   // 用 typeof 测试出来的类型都是小写的
</script>
</body>
</html>